Objective: To investigate the mechanism of tetra-arsenic tetra-sulfide (As4S4) in inducing apoptosis of acute promyelocytic leukemia (APL) cells.
Methods: The gene expression patterns in NB4 cells pre- and post-treatment with As4S4 were analyzed by cDNA microarray, and differentially expressed genes related with apoptosis were identified. The mRNA expression levels of these apoptosis related genes in the peripheral blood of APL patients treated with As4S4 pre- and post-remission were examined by RT-PCR.
Results: Among the differentially expressed genes in NB4 cells pre- and post-treatment with As4S4, two genes were related with cellular apoptosis, which were Apaf-1 and PNAS-2. Apaf1 ratio between pre- and post- As4S4 in NB4 cells was 2.910, PNAS-2 ratio was 0.420. RT-PCR results showed that the expression ratios of Apaf-1, caspase-9 and PNAS-2 in APL patients pre- and post-remission were 2.31 and 3.21, 0.99 respectively.
Conclusion: As4S4 induced cellular apoptosis in NB4 cells involves the expression changes of the two genes: the up-regulation of Apaf1 and down-regulation of PNAS-2. The increased expressions of Apaf1 and caspase-9 indicate that As4S4 induced apoptosis in APL cells is through mitochondrial pathway, but not the death-receptor pathway. The role played by PNAS-2 in cellular apoptosis needs to be clarified.